class_docstr: Stacked Bar graph class
docstr: Compute secondary y min and max
docstr_tok: ["Compute","secondary","y","min","and","max"]
code: def _pre_compute_secondary(self, positive_vals, negative_vals):
      """Compute secondary y min and max"""
      self._secondary_min = (
          negative_vals and min(min(negative_vals), self.zero)
      ) or self.zero
      self._secondary_max = (
          positive_vals and max(max(positive_vals), self.zero)
      ) or self.zero
  
file_path: pygal/pygal/graph/stackedbar.py
imports: from pygal.adapters import none_to_zero
  from pygal.graph.bar import Bar
label_desc: Use image node_id 4 for calling the StackedBar obj's underlying member method code with example usage: obj._pre_compute_secondary(positive_vals, negative_vals) without return types